General sequence control algorithm used in programmable logic controller

The invention relates to the programming of a programmable logic controller (PLC), in particular to a general sequence control algorithm used in the programmable logic controller. The method is that the programmable logic controller repetitively digitalizes the current input signal, the digitalized data is used as an input parameter for indirect addressing, information required for the next operation and control output of the programmable logic controller is obtained from a datasheet and a corresponding operation is conducted according to the information. The general sequence control algorithm used in the programmable logic controller is not limited by a controller master program (i.e. a controller master scheduling program) and a hardware, and can independently maintain the progress of acustomer program (i.e. control program), a customer program algorithm for inputting and outputting signal status, the definition of a supportive data storage structure and the specific implementationmethod.